WebAPI: much better shadowdom slot support#2720
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This adds more comprehensive and correct support for slot assignment. The
changes can be broken down into 3 buckets:
1 - Slot.assign is now implemented, and general correctness around finding/
assigning slots (e.g. Text.assignedSlot)
2 - Event dispatching for "composed" (propagating through the shadowdom) better,
specifically around the composedPath and slots
3 - The slotchange event is fires at the right time (snapshot before mutation
fire after mutation).
A number of WPT tests now pass, and there should be real-world impact for
slot-heavy frameworks (e.g. lit)
Move a lot of the Frame.slot* methods to a dedicated slotting.zig file. Frame is already quite big, and this just helps tidy things up a bit.
krichprollsch
approved these changes
Jun 16, 2026
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This adds more comprehensive and correct support for slot assignment. The changes can be broken down into 3 buckets:
1 - Slot.assign is now implemented, and general correctness around finding/
assigning slots (e.g. Text.assignedSlot)
2 - Event dispatching for "composed" (propagating through the shadowdom) better,
specifically around the composedPath and slots
3 - The slotchange event is fires at the right time (snapshot before mutation
fire after mutation).
A number of WPT tests now pass, and there should be real-world impact for slot-heavy frameworks (e.g. lit)